The present invention relates generally to semiconductor devices and, more particularly, to asymmetric double gate or all-around gate metal-oxide semiconductor field-effect transistor (MOSFET) devices and methods of making these devices.
Scaling of device dimensions has been a primary factor driving improvements in integrated circuit performance and reduction in integrated circuit cost. Due to limitations associated with gate-oxide thicknesses and source/drain (S/D) junction depths, sealing of existing bulk MOSFET devices below the 0.1 xcexcm process generation may be difficult, if not impossible. New device structures and new materials, thus, are likely to be needed to improve FET performance.
Double-gate MOSFETs represent devices that are candidates for succeeding existing planar MOSFETs. In double-gate MOSFETs, the use of two gates to control the channel significantly suppresses short-channel effects. A FinFET is a double-gate structure that includes a channel formed in a vertical fin. Although a double-gate structure, the FinFET is similar to existing planar MOSFETs in layout and fabrication techniques. The FinFET also provides a range of channel lengths, CMOS compatibility, and large packing density compared to other double-gate structures.
Implementations consistent with the principles of the invention provide asymmetric double gate and all-around gate FinFET devices and methods for manufacturing these devices.
In one aspect consistent with the principles of the invention, a metal-oxide semiconductor field-effect transistor (MOSFET) includes a first fin formed on a substrate; a second fin formed on the substrate; a first gate formed adjacent first sides of the first and second fins, the first gate being doped with a first type of impurity; and a second gate formed between second sides of the first and second fins, the second gate being doped with a second type of impurity.
According to another aspect, a method for forming gates in a MOSFET is provided. The method includes forming a fin structure on a substrate; forming a first doped gate structure adjacent the fin structure; removing a portion of the fin structure; and forming a second doped gate structure by filling at least some of the removed portion of the fin structure with gate material.
According to yet another aspect, a MOSFET includes multiple fins, a first gate structure doped with a first type of impurity and formed adjacent a first side of one of the fins; a second gate structure doped with the first type of impurity and formed adjacent a first side of another one of the fins; a third gate structure doped with a second type of impurity and formed between two of the fins; and a fourth gate structure formed at least partially beneath one or more of the fins.
According to a further aspect, a method for forming gates in a MOSFET is provided. The method includes forming a fin structure on a substrate; forming first and second doped gate structures adjacent the fin structure; removing one or more portions of the fin structure to form multiple fins; forming a third doped gate structure between the fins; and forming a fourth gate structure extending at least partially under at least one of the fins.